Idiopathic

Secondary

• Radiation

• Drugs and chemicals

  • Regular effects:

    • Cytotoxic agents

    • Benzene

  • Idiosyncratic reactions:

    • Chloramphenicol

    • Nonsteroidal anti-inflammatory drugs

    • Sulfas

    • Antithyroid drugs

    • Antiepileptics and psychotropics

    • Cardiovascular drugs

    • Gold, penicillamine, allopurinol

• Viruses

  • Epstein-Barr virus (infectious mononucleosis)

  • Non-A, non-B, non-C, non-G hepatitis virus

  • Human immunodeficiency virus (acquired immunodeficiency syndrome)

• Immune diseases

  • Eosinophilic fasciitis

  • Hypoimmunoglobulinemia

  • Thymoma and thymic carcinoma

  • Graft-versus-host disease in immunodeficiency

• Paroxysmal nocturnal hemoglobinuria

• Pregnancy